The aim of the present study was to develop an environmental analysis drawing a comparison between artificial turf football fields and urban areas relative to concentrations of particles (PM10 and PM2.5) and related polycyclic aromatic hydrocarbons (PAHs), aromatic hydrocarbons (BTXs), and mutagenicity of organic extracts from PM10 and PM2.5.

Both organic extract mutagenicity values were comparable with the organic extract mutagenicity reported in the literature for urban sites.

On the basis of environmental monitoring, artificial turf football fields present no more exposure risks than the rest of the city.

"The SVOCs identified based on library matches of their mass spectra were not present in toxicological databases evaluated and many are ubiquitous part of consumer products. Similarly, the metal concentrations measured in field samples indicate that the risk would be de minimus among all populations expected to use artificial turf fields.”

A report by an independent environmental firm on the human health and ecological risks from ground rubber in playgrounds and sports fields, and based on a thorough review of studies from advocates and opponents to the use of recycled tire materials.

The headline from the July 30, 2010 News Release from the Connecticut Department of Public Health announced, "Result of State Artificial Turf Fields Study: No Elevated Health Risk." Comprising separate reports from the four state agencies listed above, the Final Report presents the results of an extensive study into the health and environmental risks associated with outdoor and indoor synthetic turf fields containing crumb rubber infill. "This study presents good news regarding the safety of outdoor artificial turf fields," stated Department of Public Health Commissioner Dr. J. Robert Galvin.

The above link is to the Overall Executive Summary, which includes links to the News Release, the four separate reports from the state agencies, and the report by the Peer Review Committee from The Connecticut Academy of Science and Engineering (see below).

This study provides evidence that uptake of PAH of football players active on artificial grass fields with rubber crumb infill is minimal. If there is any exposure, then the uptake is very limited and within the range of uptake of PAH from environmental sources and/or diet.

Simon, Rachel, University of California, Berkeley, Laboratory for Manufacturing and Sustainability, February 2010
Prepared for: The Corporation for Manufacturing Excellence (Manex)

"The research conducted by Manex and Berkeley is among the most comprehensive reports to date, reviewing and assessing existing studies from the past 12 years, as well as containing independent analysis. The conclusions of this study validate key findings from other recent studies, demonstrating the materials are both cost-effective and safe."

Extensive research has pointed to the conclusion that these fields result in little, if any, exposure to toxic substances. A review of existing literature points to the relative safety of crumb rubber fill playground and athletic field surfaces. Generally, these surfaces, though containing numerous elements potentially toxic to humans, do not provide the opportunity in ordinary circumstances for exposure at levels that are actually dangerous. Numerous studies have been carried out on this material and have addressed numerous different aspects of the issue. For the most part, the studies have vindicated defenders of crumb rubber, identifying it as safe, cost-effective, and responsible use for tire rubber.
Recent issues that have surfaced relate to Carbon Black and Lead, however, for the vast majority of applications, serious physical harm has not occurred from these particulates.

Office of Environmental Health and Hazard Assessment, Department of Resources Recycling and Recovery, Editor. 2010, State of California

PM2.5 and associated elements (including lead and other heavy metals) were either below the level of detection or at similar concentrations above artificial turf athletic fields and upwind of the fields. No public health concern was identified.

National Exposure Research Laboratory Office of Research and Development U.S. Environmental Protection Agency, 2009

This study and statements of safety by the U.S. EPA of synthetic turf fields and playgrounds containing crumb rubber from recycled tires complements the study and statement of safety by the CPSC in 2008 (see below). In its Press Release, the EPA summarized its findings, including the following:

The levels of particulate matter, metals, and volatile organic compound concentrations in the air samples above the synthetic turf were similar to background levels;

All air concentrations of particulate matter and lead were well below levels of concern;

Zinc, which is a known additive in tires…was found to be below levels of concern.

Lim, L. and R. Walker, New York State Department of Environmental Conservation and Department of Health, Editor, 2009

Initial findings suggested that there was a low likelihood of risk to the environment or public health via drinking water from ground or surface water contamination.

Further, the concentrations of VOCs and particulate matter detected above the surface of the fields did not exceed background levels, and thus do not suggest an increased risk from the installation of these fields.

On the basis of the new observations, we conclude that, after 7 years of use, zinc does not penetrate the underlays. This is consistent with the laboratory tests, in which it was calculated that zinc leaching will not occur until a period of 230 to 1800 years has elapsed2. It can also be concluded that the concentrations of zinc in the drainage water are not significantly higher than the concentrations in the rainwater.

After 7 years, there is no evidence that the use of rubber infill poses a risk in terms of the leaching of zinc.

To date, eleven human health risk assessments were identified that evaluated exposure to the constituents in crumb rubber. Although each risk assessment was conducted using distinct assumptions and evaluated different concentrations of COPCs (chemicals of potential concern) in crumb rubber, all had a similar conclusion: exposure to COPCs from the crumb rubber may occur, however, the degree of exposure is likely to be too small through ingestion, dermal or inhalation to increase the risk for any health effect. The risk assessments have been conducted primarily by state agencies, consultants, and industry groups.

The CPSC staff conducted tests of synthetic turf products for analysis of total lead content and accessible lead. In the above News Release it concludes that, "young children are not at risk from exposure to lead in these fields.”

Review of available scientific literature and publications in order to provide an assessment about potential risks to the environment from zinc and chemicals contained in crumb rubber infill. "...water that percolates through turf fields with tire crumb is not toxic..."

Heat: On hot sunny days, surface temp of the fibers was 40-50 degrees hotter than ambient temp; air temp at 2’ above surface or under cloud cover was near ambient. Crumb rubber was only a few degrees hotter than ambient. Watering the field had a short-term effect.

Off-gassing: EHHI identified certain compounds of concern in its very limited 2007 laboratory study of the chemicals contained in crumb rubber – benzothiazole, volatile nitrosamines, and 4-(tert-octyl) Phenol. MMI tested for these compounds in the air above the synthetic turf fields with crumb rubber infill at several locations. A "very low concentration” of benzothiazole was found at 1 of 2 fields -- the other compounds were not detected.

Leaching: Testing done over one year period. Test for zinc, lead, selenium, and cadmium, and compared to lowest aquatic life criterion for each element. Only zinc detected, and then well below water quality standard.

Our review of the available information on crumb rubber and crumb rubber infilled turf fields indicates that ingestion, dermal or inhalation exposures to chemicals in or released from crumb rubber do not pose a significant public health concern.

Review of available scientific literature and publications in order to provide an assessment about potential risks of human health to children and teenagers and the risks to the environment from precipitation runoff.

According to current research, after a year’s experimentation, the results on the 42 physicochemical parameters identified and on the ecotoxocological tests show that water passing through artificial turf using as filling either virgin TPE or EPDM or granulates resulting from the recycling of PUNR are not likely to affect water resources in the short and medium term.

In conclusion to its study, the INERIS stipulates that the health risks associated with the inhalation of VOC and aldehydes emitted by artificial surfaces on pitches in outdoor situations present no actual cause for concern as regards human health.

Worst case indoor VOC and aldehyde concentrations do not pose a health concern for adult or child athletes.

Based on the available literature on exposure to rubber crumb by swallowing, inhalation and skin contact and our experimental investigations on skin contact we conclude, that there is not a significant health risk due to the presence of rubber infill for football players an artificial turf pitch with rubber infill from used car tyres.

Using the highest published levels of chemicals released by recycled tires, the likelihood for noncancer health effects was calculated for a one-time ingestion of ten grams of tire shreds by a typical three-year-old child; only exposure to zinc exceeded its health-based screening value (i.e. promulgated by a regulatory agency such as OEHHA or U.S. EPA). Overall, we consider it unlikely that a one-time ingestion of tire shreds would produce adverse health effects. Seven of the chemicals leaching from tire shreds in published studies were carcinogens, yielding a 1.2 x 10-7 (1.2 in ten million) increased cancer risk for the one-time ingestion described above. This risk is well below the di minimis level of 1 x 10-6 (one in one million), generally considered an acceptable cancer risk due to its small magnitude compared to the overall cancer rate (OEHHA, 2006).

Human health risks posed by leaching of zinc are negligible as zinc concentrations in the water do not exceed drinking water standards. The risks of zinc to public health are of no concern: the human toxicity of zinc is low and WHO drinking water criteria are not exceeded.

With the possible exception of allergic reactions among individuals sensitized to latex, rubber and related products, there was "no obvious toxicological concern" raised that crumb rubber in its intended outdoor use on playgrounds and playing fields would cause adverse health effects in the normal population.

Norwegian Institute of Public Health and the Radium Hospital, 2006, Oslo. p. 1-34.

Recycled rubber granulate contains many chemical substances which are potentially harmful to health. The concentrations of these substances are however extremely low, they are only leached from the rubber granulate in very small quantities and they are only present in low concentrations in the hall air.

It has been concluded that exposure to benzene and PAHs in the quantities in which they have been measured in the halls will not cause any increased risk of cancer using the halls.

Chemical substances are released in very low quantities; based on worst case assumptions, use of artificial turf halls does not pose elevated risk; more information needed on natural rubber allergens.

"The majority of the studies have been on higher surface area particles and have concluded they are currently acceptable. Therefore the larger granules used in artificial turf will have even less potential for emissions. For example a study undertaken by the Danish Ministry of the Environment concluded that the health risk on children’s playgrounds that contained both worn tyres and granulate rubber was insignificant. The available body of research does not substantiate the assumption that cancer resulting from exposure to SBR granulate infills in artificial turf could potentially occur.”

In comparison to the indoor fields, 7.5 percent of PM10 at an urban Switzerland curb side sampling location was attributed to tire wear particles. The fraction of PM10 attributed to tire wear particles was 2 percent at an urban background site. The levels of PM10 attributable to ground rubber measured at Norwegian fields appear to be similar in magnitude levels attributed in ambient air near roadways or tunnels. Typical ambient tire wear particle concentrations of PM10 or total suspended particulate are 2-5 μg/m3 for roadways and 10-20 μg/m3 for tunnels. Research to date has shown a highly variable distribution between fine (< 2.5 μm) and coarse (>7 μm) in airborne roadside tire wear particles.

Concentration of lead, cadmium, copper and mercury in the rubber granules is below the Norwegian Pollution Control Authority’s normative values for most sensitive land use and probably does not constitute an unacceptable environmental risk in the short or the long term.

Concentrations of zinc and PAH in the recycled rubber granules exceed the Norwegian Pollution Control Authority’s normative values for most sensitive land use. The concentrations of dibutylphthalate (DBP) and diisononylphthalate (DINP) exceed the PNEC values for terrestrial life.

Concentration of isononylphenol is above the limits specified for cultivated land in the Canadian Environmental Quality Guidelines.

Leachate from the recycled granulates contain zinc, polycyclic aromatic hydrocarbons (PAH), phthalates and phenols. The concentration of zinc indicates that the leachate water is placed in the Norwegian Pollution Control Authority’s Environmental Quality Class V (very strongly polluted water), but is lower than the permissible zinc concentration in Canadian drinking water. The concentration of anthracene, fluoranthene, pyrene and nonylphenols exceed the limits for freshwater specified in the Canadian Environmental Quality Guidelines.

The recycled rubber granulates give off a significant number of alkylated benzenes in gaseous form. Trichloromethane (sample 1) and cis-1,2-dichlorethene (sample 5) were also found.

"Genotoxicity testing of tire crumb samples following solvent extraction concluded that no DNA or chromosome-damaging chemicals were present. This suggests that ingestion of small amounts of tire crumb by small children will not result in an unacceptable hazard of contracting cancer.”

We conclude that the use of tire crumb in playgrounds results in minimal hazard to children and the receiving environment.

Extracts were not genotoxic and exposure potential in children deemed minimal; tire rubber at playgrounds does not pose a health hazard to children.

An exposure assessment performed to address the potential health risks to children playing in facilities where tire crumb is used as ground cover concluded that there was little potential for an exposure sufficient to cause ad- verse health effects in children.

U.S. EPA, National Center for Environmental Assessment–Washington Office, September 2002

Supplemental chronic risk estimates based on a child's typical incidental ingestion rate of 100 mg/day, as prescribed by the U.S. EPA’s Child-Specific Exposure Factors Handbook, indicate that regular exposure (e.g., regular play on ground rubber filled athletic fields) to ground rubber for the length of one’s childhood does not increase risk of cancer above levels considered by the state of California to be de minimus (i.e. a lifetime excess cancer risk of 10-6) or pose a likelihood of non-cancer effects (i.e. hazard index less than one).

From 67 to 160 °F, the vapor pressure of benzothiazole increases by a factor of almost 40. However, based on a study of a synthetic rubber athletic track, total VOC emissions are estimated to increase by a factor of only 2 over the same range. No exposure estimates or risk calculations were determined based on results from this study. However, total VOC concentration at breathing height above the track was 0.39 μg/m3.

Recycled rubber derived from scrap tires is a safe recyclable material. Based on the evidence presented, the overwhelming conclusion is that it would be reasonable to recommend use of recycled scrap tires in civil engineering applications.